The present invention relates generally to a method of producing a useful form according to a theoretical model, more particularly a projected useful form from an existing body delimited by a three-dimensional envelope using a tool mounted on a machine cooperating with a global satellite positioning system of the bifrequency, differential, kinematic and real time type such as GPS, the machine having at least one global positioning receiver in order to be moved according to a theoretical model of the form.
The purpose is to produce a useful form with at least one surface, defined by the movement along an arch axis of another transverse curve, in general polygonal, possibly variable. Such a surface is referred to as a topographical profile. Such a profile must be as close as possible to a projected theoretical profile referred to as a model.
This model, for example defined by means of computer aided construction software, represents the useful form to be produced. In practice, these useful forms have faults or imperfections compared with the model, which it is necessary to remove in order to ensure that this form meets the requirements. Thus, in order to evaluate the quality of evenness of road projects, a notation system has been set up.
These defects are detected by physical measurement in situ and quantified from a numerical analysis of the unevennesses along the profile of the roadway, by physical measuring appliances. The magnitude of these defects is between a few millimetres for the smallest, and a few tens of millimetres for the largest. According to the magnitude measured, a grade known as the LPA (Longitudinal Profile Analysis) grade lying between 0 and 10 is attributed to the useful form. The grade 0 is then attributed to a useful form whose defects have a magnitude of a few tens of millimetres. For defects whose magnitude does not exceed a few millimetres, the grade 10 is attributed to the useful form.
To produce such useful forms in practice, three techniques are normally employed. One technique consists of guiding at least one site machine along wires installed on site. These wires give physical expression to the arch axis which the machine must travel along. In practice, wire guidance does not make it possible to produce useful forms having one or more complex surfaces as easily and rapidly as simple useful forms. This is because only two dimensions in space are apprehended, and the notation of the useful road forms thus obtained does not in general exceed 6.
Another technique consists of guiding site machines along laser beams, which give physical expression to the arch axis, formed by one or more straight sections, which the machines have to travel along in order to produce the useful form. The successive positionings of the machine are obtained from its initial position, considering that it follows the arch axis, by measuring the distance travelled from the origin, calculating, by means of the laser, an actual position of the machine with respect to the curve, and attempting to make this position coincide with the required curve. When useful forms are produced having one or more complex surfaces, this guidance requires frequent repositioning of the lasers.
In addition, because of the optical nature of the laser, it is essential to avoid the interposing of physical obstacles between an optical source and its receiver. However, such obstacles, such as other machines on the site (compacter, bulldozer, lorries, earth movers or the like) frequently cut the laser beam, requiring interruption of the operation or production guided by the laser.
In addition, geometric variations within certain useful forms complicate or even prevent the use of laser guidance: interchange roads can for example be cited.
Finally, the use of a laser is complex or even possible for useful forms whose arch axis has small radii of curvature, such as in road interchanges.
Yet another known technique consists of using GPS systems. The document U.S. Pat. No. 5,631,658 can thus be cited, which describes a machine guidance method, for an earthwork machine for example, by means of a GPS system. This document makes provision for storing a first three-dimensional model representing the required geography of a site, and a second three-dimensional model representing the actual geography of this site as it is produced. The two models are compared with means which represent, in digital signals and in real time, the instantaneous three-dimensional position of the machine whilst it is travelling on the site. Other means determine and update the difference between the two geographical models, in real time. Whilst the means control the machine, according to this difference.
One drawback of this method is that it requires computer storage and processing means capable of taking the two three-dimensional models into consideration, which turns out to be complex to implement in practice. In addition, in the useful forms having several juxtaposed surfaces, it is difficult in practice to obtain precise connections between these surfaces, with the known GPS guidance systems. Also, the known GPS guidance systems do not make it possible to work indifferently in one direction or in the other along the arch axis, which requires a certain amount of rigidity in the working method.
The invention therefore aims to permit the production of useful forms, dispensing with the drawbacks mentioned above, amongst others.
One aim of the invention is thus to permit the production of useful forms for road projects, whose LPA notation is greater than 8, preferably equal to 10, with a precision in terms of elevation of xc2x113 mm. To this end, a first object of the invention is a method of producing a projected useful form such as a road project surface, from an existing body delimited by a three-dimensional envelope, such as a construction site, building or the like, using a tool mounted on a machine, for example an earthwork machine for a site or similar. This machine cooperates with a global positioning by satellite system of the dual-frequency, differential and kinematic type and in real time, such as GPS; and has at least one global positioning receiver, for example on a tool, in order to be moved according to a theoretical model of the useful form.
According to one characteristic, this method includes the steps making provision for:
storing fixed geometric curves peculiar to the useful form, including at least one substantially longitudinal arch axis and at least one cross-sectional profile;
measuring, at at least one moment, the elevation, longitudinal and transverse position of the tool, using a global positioning receiver when the tool is moved, for example at a predetermined frequency;
associating a position along the arch axis with this measured position;
locally calculating the theoretical model whilst making a cross-sectional profile of the useful form correspond to this location;
activating in memory a standard deviation signifying an uncertainty characteristic of the global positioning system, possibly after it is determined during a phase of calibrating the receiver;
comparing, during the movement of the tool, for example at a predetermined frequency, a measured elevation position of the tool with a theoretical altitude defined from the model;
deducing from this comparison a deviation in elevation at the time of measurement, such that this deviation is said to be a zero deviation when the measured elevation position is substantially the same as the theoretical altitude;
defining on the one hand at least from the zero deviation at least two analysis bands, for example two centre bands respectively upper and lower, two median bands respectively upper and lower, and two external bands respectively upper and lower, these bands being for example symmetrical in pairs, lower and/or,upper delimiters of these analysis bands being proportional to the standard deviation;
identifying an active analysis band to which this deviation in elevation belongs;
calculating, according to the deviation and the active analysis band, an elevation slaving reference, a ceiling for whose value is set according to the active analysis band identified; and
controlling the elevation position of the tool according to the calculated reference, so that this tool is either momentarily left in position, or brought closer to the model, in a limited fashion, by an elevation distance substantially proportional to the absolute value of the reference.
According to another characteristic, the theoretical model of the useful form is calculated locally from notably at least:
the arch axis, defined mathematically, notably by a line known as the axis in the horizontal plane and by a longitudinal profile, defined themselves by at least one continuous and derivable parameterised function, and including at least part of a geometric curve, and for example a succession of such parts, each being defined mathematically by a simple continuous parameterised function, such as a straight line, arc of a circle, parabola, clothoid or the like; and
a cross-profile, defined mathematically by a continuous parameterised function, for example each cross-profile is a succession of end to end straight line segments.
In one embodiment, the method of the invention is also intended for re-establishing a useful form. To this end, the method includes, during the storage of geometric curves, at least one phase making provision notably for a measuring pass of the existing useful form, for example with a machine similar to that provided for effecting the re-establishment.
In addition, the method of the invention provides for a lateral or directional step of controlling the longitudinal path of the machine and/or of the tool during the production of the useful form, this step including the phases making provision for:
defining an auxiliary guidance line-which must be followed by the machine during a given pass of the production, this guidance line being for example at a substantially constant distance from the arch axis;
analysing the measured lateral position in the longitudinal plane of the tool according to the measurements supplied by the receiver; and
according to the parameters obtained by this analysis, calculating a lateral slaving control of the machine able to make a trajectory of the machine in the horizontal plane coincide with the auxiliary guidance line.
In addition, on the one hand at least from the zero deviation three analysis bands are provided, namely:
a first analysis band close to the zero deviation, said to be centre and defined by a set of deviations;
a second analysis band, said to be median and defined by deviations greater than those of the centre band; and
a third analysis band, further away from the zero deviation than the centre and median bands, said to be external and defined by a set of deviations greater than those of the median band.
The invention concerns a method of producing a useful form according to a theoretical model, on or from a body delimited by a three-dimensional envelope such as a construction site, a building or the like, using a satellite global positioning system such as GPS or the like. The invention also concerns a control and slaving device implementing the method.
The invention also concerns a machine intended for producing such useful forms.
Finally, it concerns a useful form, for example at least part of a sheet, a deck or volume, a civil engineering edifice, a building or an industrial installation.
By way of example, an application of the invention can be mentioned for carrying out linear road, railway or airport projects, or non-linear projects such as industrial platforms. In such designs, the invention relates to the earthwork operations, and the operations of spreading, nibbling and pouring concrete notably. For these designs or operations, it is frequently necessary to obtain, with a high precision, at least one surface which is at a minimum fine tuned, and possibly complex. Obviously, similar requirements need to be complied with for producing concrete interceptors for roadways cast in situ, edges of pavements, gutters or roadways, and for the burying of pipes, for example petroleum pipelines.
For this purpose, in the example mentioned above, one or more site machines are controlled and/or guided in order to put in a useful form materials such as fill, concrete, bituminous material or similar.
In one embodiment other analysis bands are provided on each side of the model and/or of the zero deviation, for example symmetrical with the centre, median and external bands with respect to the zero deviation. The analysis bands being symmetrical, for example greater and lesser with respect to the zero deviation, the processing of all the deviations considers only their absolute value, the reference corresponding to a deviation of negative sign being equal to the opposite of the reference issuing from the processing of the absolute value of this deviation.
According to another characteristic, the theoretical model is in a position to have the machine running through it along the arch axis and/or along an auxiliary guidance line, freely in one direction or in another direction, for example opposite.
In one embodiment, the method of the invention includes a step of automatic recognition of the direction of movement of the machine along the arch axis and/or the auxiliary guidance line. In addition, at least two successive passes are provided for, for example in elevation, an auxiliary initial guidance line, relating to an initial pass, then being translated in elevation by a predetermined value in order to define a subsequent auxiliary guidance line, relating to a following pass. According to one characteristic, the frequency of measurement, processing and calculation is defined, between a measuring time and a following subsequent measuring time, by a clock in the global positioning system, and is for example around 1 hertz.
In one embodiment, the processing of the deviation according to the method of the invention operates as follows. On the one hand, if the deviation is determined in an external analysis band, then the slaving reference, is of constant value, for example its absolute value corresponds to a tool movement distance of around 10 millimetres. On the other hand, if the deviation is determined in a median analysis band, then there is calculated a so-called median difference or quantity defined by a difference between this deviation and a respective delimiter of this band closest to the zero deviation, a slaving reference being deduced from this quantity. When the absolute value of this quantity is greater than a maximum median action value, then the absolute value of the slaving reference is determined as being substantially equal to this value, for example this value corresponds to a tool movement distance of around 10 millimetres. When the absolute value of this quantity is less than a minimum median action value, then the absolute value of the reference is determined as being substantially equal to this value, for example this value corresponds to a tool movement distance of around 4 millimetres. Whilst when the absolute value of this quantity is between maximum and minimum median values, then the absolute value of the reference is determined as being substantially equal to the absolute value of this quantity.
Finally, if the deviation is determined as being in a centre analysis band, for example upper and lower, then there is effected a step of calculating a so-called centre difference between the absolute value of this deviation and the absolute value of a deviation at a calculation time immediately preceding according to the value of the frequency of processing. When this centre difference is negative or zero, then the reference is chosen so as to be substantially zero, and for example the tool approach elevation distance is zero. When this difference is positive, there is calculated a so-called centre quantity, equal to a fraction of the difference, for example around one third of this difference.
If the centre quantity is greater than a maximum centre value, then the absolute value of the reference is determined as being substantially equal to this value, for example this value corresponds to a tool movement distance of around 4 millimetres. If the centre quantity is less than a minimum centre action value, then the absolute value of the reference is determined as being substantially equal to this value, for example this value corresponds to a tool movement distance of around 1 millimetre. Whereas if the centre quantity is between the minimum and maximum centre action values, then the absolute value of the reference is determined as being substantially equal to this centre quantity.
In one embodiment, there is calculated a regression curve, for example a straight line, which defines the mean change in the deviations deduced during a predetermined interval of time, for example between the times of a prior measurement and a preceding measurement. A regression deviation is extrapolated from this regression curve, and the reference corresponding to the deviation deduced from the difference between a measured elevation position and a theoretical altitude is then corrected according to the difference between this deviation and the extrapolated deviation. The correction applied to the reference makes provision for replacing, in the calculation of this reference, on the one hand the value of the deviation by the value of a corrected deviation, and on the other hand the value of the previous deviation by the value of a previous corrected deviation. The values of the corrected deviation and of the previous corrected deviation are respectively equal to a weighted mean of the value of the deviation and the corresponding extrapolated deviation, and to a weighted mean of the value of the previous deviation and a corresponding previous extrapolated deviation.
According to one characteristic, signals or frames received from the receivers for processing are subjected to decoding and filtering operations, these operations transforming the frames into digital signals able to be processed, and eliminating all the measurements whose deviation with respect to a previous measurement is greater than a predetermined higher value, for example around 100 mm. In addition, a digitisation step is provided by a digitisation module. This digitisation step includes notably the phases of:
digitising data relating to the theoretical model for example issuing from a computer aided design;
simulating the movement of the machine on the theoretical model, in order to check the consistency of the data;
display of parameters of the theoretical model; and
creating computer files able to be processed by a computer controlling the method.
In one embodiment, the theoretical model is notably defined by the arch axis and at least one cross-sectional profile, a step being provided of calculation, by linear interpolation between different cross-sectional profile parameters of the theoretical model, successive or continuous along this arch axis. In addition, an automatic step of identification of error in the limited convergence and/or the processing is provided, such as at least one absence of position measurement by the receiver, a lack of communication, an error in digitisation of the theoretical model, an error in transmitting the global positioning information to a computer, an error in calculating slaving, or a positioning error peculiar to the machine.
The method of the invention also provides for the use of at least a second receiver and/or at least one attitude sensor, for example an inclinometer or a camber sensor, and provides three distinct operating modes: a so-called priority mode to the left of the tool, a so-called priority mode to the right of the tool, and a mode without priority, notably for producing broken or similar cross-profiles of the useful form.
A second object of the invention is a control and slaving device intended for producing a theoretical model of a projected form from a body delimited by a three-dimensional envelope, able to implement the method of the invention.
According to one characteristic, this device comprises notably at least:
a positioning module;
a computer able to process information coming from the positioning module and a useful part only of the theoretical model, accessible for example by means of a file;
a digitisation module;
an automatic controller, for example programmable; and
elevation distributors respectively right, left and tool direction.
The computer of this device comprises notably at least three sub-systems, namely:
a decoding and filtering kernel;
a location kernel; and
slaving means connected to the elevation and direction control valves of the tool by means of the automatic controller.
According to one characteristic, these decoding, filtering and location kernels contain digital calculation computer programs, applications resulting from digital calculation software or the like. Moreover, the device of the invention comprises means of transmitting to the computer, at any time, information in the form of coded messages, notably relating to a longitudinal, transverse and elevation position of each mobile receiver. In addition, this device has security means, able to detect or identify a stoppage in functioning of the mobile receivers and/or able to cause this device to switch from an automatic functioning mode to a manual functioning mode according to which a driver of the machine entirely controls the latter.
According to one characteristic, this device comprises means of automatically recognising the direction of travel of the machine along the arch axis and/or an auxiliary guidance line of the theoretical model.
A third object of the invention is a machine able to implement the method of the invention and/or containing at least one device of the invention, such as an earthworks bulldozer, a fill tipping skip, a continuous concrete pouring machine, an existing structure nibbler, a snow plough or the like.
According to one characteristic, this machine has at least one tool with at least one global positioning receiver, for example two receivers, mounted on respective masts close to the transverse ends of the tool.
According to another characteristic, this machine has at least one tool with at least one global positioning receiver for example close to the transverse ends of the tool and at least one attitude sensor. In addition, this machine is provided for example with a cab for a driver of this machine, and display means such as a screen, for example liquid crystal or the like.
According to one characteristic, these display means include at least one welcome and parameterising screen, a working screen and a geometric information screen, the welcome and parameterising screen being for example a touch screen to enable a driver of the vehicle to initialise a control and slaving device.
According to another characteristic, the machine of the invention has automatic means of slaving its steering, for example controlled by a control and slaving device of the invention, these steering slaving means being able to automatically make a movement path of the machine converge towards and along an auxiliary guidance line.
In one embodiment, the machine of the invention has means of adjusting the transverse position of the tool about an elevation direction, able to allow the limited convergence of the path of this tool to and along an auxiliary guidance line. In addition, this machine has notably a steering lever and priority determination means for an automatic mode, this determination making it possible, by means of a movement of this lever operated by a driver, to make the functioning of the control and slaving device of the invention pass from an automatic mode to a manual mode.